23D refrigerator fan and compartment mods

[Troutboy]

There are many other posts on the forum about modifications to the fans on AS fridges to install a quieter option. After playing around with my fridge and new AS I quickly decided to replace the fridge fan with a quieter option (based on the other posts). I did this very easily with one silenx replacement fan and it was great, very quiet.

However, after running the fridge for three days, I was concerned with the amount of heat buildup and combustion smell in the AS. Our AS is a 2017 FC 23D. This AS does not have a vent exhaust to the roof. Rather it has two side vents, an upper and a lower, with one small fan fastened directly to the coils on the back of the fridge. The first picture shows the original factory fan. The second pic is the replacement fan.

Factory Fan on coil:


Replacement Fan on coil:


This replacement was easy, a 92mm silenx from amazon. The fan popped out of the plastic holder and I popped it back in. It ran very quiet as stated above.

My concern became the fume smell and the heat buildup in the fridge compartment that was intense. In the wardrobe and microwave compartments, I could barely touch the walls and you could feel the heat radiating off this surface. The fume smell was strong in the AS (I have a sensitive sense of smell).

I decided I needed some serious fan help to improve the flow and carry the fumes and heat out. I really liked a post by switz, and he sent me some pics that he posted where he used three fans and sealed off the upper vent except for the fans, to force the air into the bottom vent and prevent air short circuiting.

I'm an environmental engineer, and this made sense to me. Others had concerns with this design as they thought it would hamper airflow when the fan was not in use. I plan to always use the fans, so not concerned. My new solar system and batteries will easily keep up with the 0.3A draw. To be on the safe side, I thought I would design it so I could easily remove the baffle if I wanted.

Switz's design was excellent and clean, but installed by taking out the fridge. I didn't want to do this, so I made my own mods using aluminum angle bracket and aluminum sheet metal. I chose three high flow 120mm silenx fans to move air, and set it up so I could easily take it down/apart, disconnect a fan, etc (I used standard computer fan connections that are easy to install and remove.

I also installed a master on off switch in then AS near the LP detector, so I can turn it on and off manually as needed. These fans are not tied to the thermostat at all. The single fan on the coil is setup to operate off the thermostat (it works fine as tested with a heat gun).

Fabrication was simple, used a jig saw to cut the aluminum brackets, a table saw to cut the sheet metal, riveted the brackets together, used sheet metal screws to assemble the rest so it was easy to take off as needed. To mount the fans I used the rubber fasteners provided with the fan to dampen vibrations and isolate the fan noice from the frames.

Pics below:








I placed the fans more towards the right of the opening., since that is where the exhaust from the boiler is located.

The system works awesome, and after testing it for three days, never ran batteries down at all. They would decrease at night by 2% or so, but they were recharged 100% by 6 am every morning based on very little sun. Confirmed amp,draw at 0.3A.

The noise can barely be heard in the AS. It's not silent, but much quieter than the fantastic fans or the hum of a house fridge. I don't think it will pose any sleep issues, but if it does, we can just turn it off. The noise is more pronounced on the outside by the vent, but much quieter than say the single factory fan or the furnace running.

Most important, there is no fume smell in the trailer and barely any heat increase in the wardrobe or microwave. I am sure this will also help the fridge stay cool as it moves quite a bit of air past the fins etc. I did these tests with both vents closed as well. High temps reached low to mid 70. No need with this air flow to keep the vent opened.

I feel this is much safer now. Easy fab and install, no special tools needed.

[OTRA15]

Great job! Thanks for the photos and text. BTW did you notice the new 23D thread?

http://www.airforums.com/forums/f142...ad-166085.html

[Troutboy]

Didn't see it yet Peter, thanks for the link!

[dkottum]

I think it's great when the fans are running, but dangerous if for some reason they stopped running. We have the two door fridge as well, and can keep the compartment much cooler by simply propping open the top hatch, or both.

If you smell combustion fumes inside the Airstream, have the fridge mount in it's compartment inspected. It should be air tight, inside air seperated from air and fumes in the fridge compartment. That adds another level of danger to the mod should the fans stop running.

[Troutboy]

If the fans stop, I can remove the seal partially or completely with taking out 7 screws.

Good point on the seal, I will check that out for sure,
Thanks!

[RFP]

Great mod and nicely done... looks very "professional' (well, actually better!).

Rob

[Hoboplayer]

Like all Airstreamers I have modified my ref. cooling fan. During the change I lost track of the direction of flow. Does it mater. I have side vents.

[Troutboy]

Depends on whether you want the air blowing in, out or up down. Usually there are some arrows on the side that tell rotation and airflow. I also think that most have the air blow out the side with the sticker on the hub, if that makes sense.

[Troutboy]

I made an upgrade to my fan mod after first trip out. Three fans is great, but not always needed, especially at night. I wanted to figure out a way I could reduce the number of fans.

I came up with the idea to put switches on the outside that would allow me to toggle the number of fans running at any given time.

Here is my solution, and it works great. I will have to fabricate a different left panel, since the last switch is not in line with the others, the drill slipped and being so close to the edge it ripped a large hole.

[KJRitchie]

So on these side vented fridges, is there a cavity above the upper fridge vent door frame for heat to collect and are the condenser fins are in that cavity? Looking at your first photo there is quite a gap between the tubes and the outside shell. Shouldn't Airstream have baffled the wall between the top and bottom vents. It appears Airstream isn't following the installation guidelines very well.

Kelvin

[RFP]

Originally Posted by KJRitchie

So on these side vented fridges, is there a cavity above the upper fridge vent door frame for heat to collect and are the condenser fins are in that cavity? Looking at your first photo there is quite a gap between the tubes and the outside shell. Shouldn't Airstream have baffled the wall between the top and bottom vents. It appears Airstream isn't following the installation guidelines very well.

Kelvin

Kelvin,

You are exactly right... there is a huge cavity above the opening door/grille and the coils are tucked up tight at the top of this cavity. It's even worse than the installations done by Casita. Troutboy and Switz have done an excellent job of fixing the results of Airstream apparently ignoring the installation guidelines.

I think a wireless temperature monitor, with an audible alert feature for "too high temperature" would be a good thing to have with this "fix."

[montanablue]

Cool

[Troutboy]

Kelvin,

I opted to not move the baffle and kill it with airflow. It worked well the first time out. Time will tell. I may have to baffle it more like Switz.

Also, Boog did a nice baffle mod, post below:

http://www.airforums.com/forums/blog...-upgrade-2632/

[Troutboy]

Update:

Spent 5 nights in mountains with the AS. Temps in the day approached 83 degrees, and direct sunlight. The system worked great, fridge stayed at temp of 34 entire time.

HOWEVER> at one point the fans were turned off (I think the kids hit the off button by accident). I noticed fridge temp was in low 40's around mid day, and checked system, thats when I saw fans were off. I turned them back on, and it immediately dropped temp back to 34 (over an hour or so).

NOTICE: If you do this mod or one like it, the fans will be required to run at al times in warm weather, as closing off the top vent will hinder airflow when fans are not on, resulting in heat buildup.

[jftompkins]

Am wondering if the airflow in the condenser is the main issue (finned tube exchanger) being located right up against the top seal such that air flow (mass flow for heat transfer) has to take a slight path downward (U-Turn), and then a 90 deg turn out through a louvered/screened vent....alot to ask for - too much pressure drop; and probably very little mass flow through the exchanger (as designed for). The condenser is dependent on natural circulation (convection) of cool air to rise through the fin surfaces due to the warming of the air pulling it vertically through - straight up. Albert Einstein I believe was actually involved in designing this refrigerator cycle - purpose ' ...develop an energy efficient absorption refrigerator with no moving parts."

So back to Einstein's intent "No moving parts". Would it be possible (AS design group); to raise the top seal as well as the side vent 6-8"...to allow the natural circulation for the condenser heat exchanger to happen?...it might even work on hot days?

[Boog]

I hated that 2.25” dead air space above the refrigerator and behind the condenser coils – it collects and holds heat. The sides of the refrigerator have some recessed rubber gaskets to help isolate the sides of the fridge from the heat, but the top has nothing - because the coils are too close to the ceiling and there wouldn’t be enough room to slide the fridge out for service.


Then a lightbulb went off… how about a piano hinged baffle? Open it up flat to slide it over and behind the coils, then flip it down 90 degrees to block the opening and voila – instant baffle that will fold up and out of the way if the fridge is pulled out. I made the down leg longer with a 2.25" strip of aluminum riveted to the hinge.


Now, how can I insulate that dead air space above the fridge and behind my new baffle? I pulled the microwave and roto-zipped an access hatch into the bottom, stuffed 2.5” of fiberglass insulation in the hole. All that I have to do now is get out and see if it helped!

[RFP]

Originally Posted by Boog

< snip > I pulled the microwave and roto-zipped an access hatch into the bottom, stuffed 2.5” of fiberglass insulation in the hole. All that I have to do now is get out and see if it helped!

Good day, Boog!

I'm wondering if after you stuffed that fiberglass insulation on top of the refrigerator if you replaced - and sealed - the panel you cut out with your Roto-Zip? It seems to me that left open, there would be a path for combustion products from your refrigerator to infiltrate your coach when running on propane. I know it's a pretty "obstructed" path, but I'd think ANY combustion products inside is a bad thing.

Rob

[Boog]

Hey Rob, Good point on the fumes - Yep, I flanged the cutout piece, stuck it back in the hole, screwed it down and sealed it up. Plugging the microwave back in was almost as hard as the rest of the project!

[Bruker]

[I][QUOTE=Troutboy;1943050]There are many other posts on the forum about…

Troutboy. Am following your mods. Successful fabrication of baffle and fan mounts. Can you help with a wiring scheme?

[ITSNO60]

I am also working on this mod. The fans used by Troutboy are no longer on Amazon, Troutboy can you tell us the cfm of the fans? There are so many choices out there. I am considering these 200mm fans: https://www.amazon.com/dp/B009XERK6G...v_ov_lig_dp_it

very quiet and 76 CFM, I have room for two but I am debating whether to use one or two, 76 CFM is quite a bit of air changeover for that little space (there are some bath fans rated at only 50 CFM) plus the design of my vents doesn't have a lot of holes for the exhaust and I am afraid too much CFM will cause back pressure and turbulence. I plan to fully shroud whatever I use, working on the shroud now.